Oh where to begin there are so many dice apps out there. Some are simply RNG (Random Number Generators) some are physics based dice applications.  Man some of them look so very beautiful and others are pure utilitarian. But it has been my experience and that of most everyone that I know to nearly a man. Unless you have forgotten your dice and no one, NO ONE! is willing to let you borrow a set. You will never EVER have the chance to use a dice app over physical dice in hand.  So fist off I will say avoid paying money for any dice apps unless they bring more to your game experience than dice rolls. Your money will be better off used to buy a set of physical dice that you can chuck in your glove box for emergencies.
So, Are there any good Dice apps out there that are worth it. Say you want something on  your phone or Ipad and don’t want to run to the car to get your dice.
At this time hands down probably the best and only pick for a pure dice roller App would be Dice and Dragons.

The app allows you to save multiple profiles and mixed dice rolls for re rolls later for when you need that big fireball to come online. And it also allows you to assign sound affects to your dice as well.  It has an in App purchase for other fancier dice but you can sill get full use out of this app for free. Percentile dice are not included in the free app but it is just as easy to roll the dice and read from left to right.
This App will do you no good for any funky dice systems like Star Wars, FATE or DCC.
As for FATE there are no pure Dice rollers, so we will touch on that in another post.

The next pure dice roller app that would cover your PRG needs is from FFG.
This app costs a pricey 4.99 but you might actually get to use it more than other dice apps. This app comes with a regular set of D4-20. In addition to that it also has the new Star Wars Edge of the Empire dice set.  If you play Star Wars Attack wing this App has a Dice roller for this game also. Here is to hoping that they will add the dice for the new star wars rebel assault into this app .The App will auto calculate the dice results for your EOE games if you opt for it in the settings.
The Star Wars App can be found on both the Apple Store and Google Play Store.

Will Dice apps speed up your game or bring anything new to your game experience ? Not enough to warrant purchasing dice unless you have the spare change and your Gamemaster allows Dice apps at your regular game. In the end I would still encourage to just stick with Physical dice. It will save you time, Batteries and any issue that might come up between you and your GM. Save your cash there are better apps out there and many of them have built in dice rollers.